純チタン膜材のすべり面と疲労き裂進展機構の相関

抄録

The cold-rolled pure titanium film has a rolling texture in which the c-axis is inclined by 30 degrees with respect to the rolling perpendicular direction. The film was adhered to a through elliptical hole in a base plate and was fatigued in accordance with the displacement constraint along the hole circumference in the base plate subjected to a cyclic stress. Commonly, a stress intensity factor range was increased with a crack propagation under a constant stress amplitude but was decreased toward the hole edge because of the difference in thickness between the film and the base plate in this ΔK-decreasing test method. After a fatigue test, an active slip plane is identified by using the Electron Back-scatter Diffraction (EBSD) system. As a result, the fatigue crack propagation rate decreased with decrease in the angle between the loading direction and the rolling direction. The fatigue crack propagated by prismatic slips in the film loaded to the rolling direction and by basal slips in that loaded to the rolling perpendicular direction. The ratio of prismatic planes to basal planes decreased with decrease in the angle between the loading direction and the rolling direction.